Make Slime, Gak, and Oobleck | Gross Science

Tami O'Connorby: Tami O’Connor

Let’s face it, kids of every age love gooey substances! The school year is never complete until you and your students make slime. Depending upon your grade level, the topic you’re teaching, your classroom budget, and the time you have available, there are a number of options open to you.

One of my favorite “recipes” is the ever popular Elmer’s Glue Gak. Aside from the fact that it’s easy to make, it’s rare that you wouldn’t have most of the essential ingredients at your fingertips.

Borax and Elmers Glue for making SlimeTo make Gak:

You will need equal parts of Elmer’s glue-all and water. I tend to use two cups side by side and pour about 1/4 cup of glue in one and an equal amount of water in the other. Students can easily judge if the two liquids are equal without messing around with measuring cups. Pour the Glow-in-the-Dark Pigmentwater into the glue and stir well. At this point, you can add food coloring, or better yet, phosphorescent powder so your gak will glow in the dark. If you’re using food coloring, only 4 or 5 drops are necessary.

In a separate cup you will need to mix hot water and Borax (sodium tetraborate) until you have a saturated solution. 20 Mule Team Borax can usually be found in your grocery store in the laundry aisle. I explain to my students that the water is saturated when the powder no longer dissolves in it. Evidence that you have a saturated solution is when the powder remains on the bottom of the beaker or glass even after the liquid is stirred well.

While mixing the glue mixture, slowly add the Borax solution. Students will immediately find that the glue mixture begins to clump and turn from a liquid to more of a putty-like solid. This is because the sodium tetraborate is a cross linking agent that hydrogen-bonds with the long polymer molecules found in the Elmer’s glue.

Another favorite gooey activity is slime making…. For this, I always use polyvinyl alcohol. I love using the hot water soluble Polyvinyl Alcohol BagsPolyvinyl Alcohol Bags commonly used in hospital laundry rooms. Typically, these bags are used to place soiled linens within them reducing the chance that a hospital worker will come into contact with contaminants. When the bag, filled with sheets etc. is thrown in the washing machine, the hot water dissolves the bag exposing the linens to the water and detergent. When the water leaves the washing machine, so does the dissolved PVA.

To make Slime:

Make Slime & Glowing Slime Kits

To make slime, dissolve the PVA bags in hot water (the appropriate amount is in the directions), and then slowly stir in the same Borax solution used to make Gak. The basic difference between slime and Gak is textural and color. Gak is opaque while slime is more transparent, and slime tends to be a little thinner and less putty-like. As with Gak, slime can be colored by using a couple of drops of food coloring before adding the Borax solution.

Make Slime KitFor those teachers who have less time to spare, Educational Innovations carries a Classroom Slime Kit that has everything you need premixed. All you have to do is combine the PVA solution and Borax solution and voila… instant slime!

Finally, the gross fluid that behaves like a liquid and a solid; Oobleck! When allowed to sit in its container, Ooblek behaves like a liquid. As soon as pressure is applied, this non-newtonian fluid behaves like a solid. It can be rolled into a ball, but then as soon as you stop rolling, it “melts” in your hands! Kids love experimenting with this material!

To make Oobleck:

Oobleck is easily made by using 2 parts cornstarch to one part water. If you are planning to color your Oobleck, it’s easiest to color the water you add to the cornstarch. Finally, if you are working with younger children, the perfect literature connection is Dr. Suess’s Bartholomew and the Oobleck.

Clean-up for any of the gooey mixtures is fairly simple. A warm soapy sponge should clean most flat surfaces. It’s a good idea to keep any of the polymers away from clothing or carpeting, especially if you use food coloring. With the exception of the Borax solution, I would avoid putting anything else down the drain, but putting them in the garbage can should be fine… Be sure there is a plastic liner in the can or you will not be the custodian’s favorite teacher!

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